This brief presents a pulsewidth modulation buck converter with an adaptive ramp amplitude control. The proposed buck converter can improve the load transient response and the reference tracking speed. A chip was fabricated in a 0.18-μm CMOS technology. Measurement results showed that the overshoot/undershoot at the output during the load transient period was reduced by up to 57% for a 450-mA load current step and that the reference tracking speed was improved by up to 71% for a 1.5-V output voltage change. The measured maximum power conversion efficiency was 92.6% at 3-MHz switching frequency when input and output voltages are 3.3 and 2 V, respectively.
In this letter, we present an injection-locked Class-E power amplifier (Class-E ILPA) suitable for 2.4-GHz wireless sensor network applications where the maximum transmit-power is typically about 10 dBm. In such a low transmit-power application, it is a great challenge to achieve a high transmit efficiency because the driving power and dc power consumption in the previous stage are no more negligible compared with the transmitted signal power. The proposed Class-E ILPA, which is fully integrated in 0.18-m CMOS technology, achieves the power added efficiency of 44.5% while delivering the output power of 11 dBm with drain efficiency of 49.3% at 1.2-V supply voltage. The measured locking range reaches 300 MHz with the input driving power of 6 dBm.Index Terms-Class-E power amplifier (PA), injection-locked (IL), power oscillator, wireless sensor network (WSN).
A 2.4-GHz fully integrated CMOS receiver front-end using current-reused folded-cascode circuit scheme is presented. A configuration utilizing vertically stacked low-noise amplifier (LNA) and a folded-cascode mixer is proposed to improve both conversion gain and noise figure suitable for sub-mW receiver circuits. The proposed front-end achieves a conversion gain of 31.5 dB and a noise figure of 11.8 dB at 10 MHz with 500-A bias current from a 1.0-V power supply. The conversion gain and noise figure improvements of the proposed front-end over a conventional merged LNA and single-balanced mixer are 11 dB and 7.2 dB at 10 MHz, respectively, with the same power consumption of 500 W.Index Terms-Conversion gain, current-reusing, flicker noise, folded cascode, noise figure, signal-to-noise ration (SNR).
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